1. Technical Field
The present disclosure relates generally to firearms and relates more particularly to high capacity box magazines for feeding cartridges to firearms.
2. Related Art
Removable magazines for feeding cartridges to firearms are well known. There are generally two main types of magazines, i.e., box magazines and drum magazines. Box magazines are generally limited to about 30 cartridges, so as to maintain reliability. Drum magazines typically hold 50-150 cartridges. Because of their lower capacity, box magazines must generally be changed more often than drum magazines. Box magazines are much lighter, simpler, and more compact. A person may carry more cartridges loaded in box magazines than drum magazines. Drum magazines are generally preferred over box magazines for high capacity applications.
It is desirable to provide magazines having high capacities. The use of magazines having high capacities requires less frequent magazine changes than the use of magazines having low capacities. The use of high capacity magazines better assures that the firearm will be ready to use when needed.
Because of their higher capacities, drum magazines require less frequent magazine changes as compared to box magazines, but drum magazines are much heavier, more complicated, and are comparatively bulky. Although drum magazines initially provide greater firepower, their weight and bulk reduce the amount of ammunition (held in magazines) that a person may carry. One option is for a person to carry a drum magazine (such as a 100-shot drum magazine) on the firearm for initial firepower and to carry the rest of the ammunition in box magazines (such as 30 round box magazines). However, such an approach is often impractical due to the bulk of the drum magazine and due to the number of box magazines required, for example.
It is desirable to combine the large capacity of a drum magazine with the light compact size and portability of a box magazine, so as to obtain both the greater initial fire power of the drum magazine and the greater sustained firepower of a plurality of box magazines. However, as the size of a magazine is increased to accommodate more cartridges, a longer, higher force spring must generally be used to move the cartridges within the magazine. As the capacity of a magazine is increased, each added cartridge tends to reduce the reliability of the magazine. For example, the higher force provided by the higher force spring, particularly when fully compressed, may cause undesirable feed problems that render the firearm temporarily inoperable.
According to conventional methodology, increasing the capacity of a conventional double column box magazine from the 30 cartridges common today to 100 cartridges would undesirably more than triple the length of the magazine and would also require three and one third times the force to accelerate the three and one third times the weight of cartridges in order to lift the top cartridge up into the feed path of the firearm as fast as is accomplished when using a conventional 30 cartridge magazine (such as a 30 cartridge magazine for which most automatic firearms are commonly designed). Such conventional firearms would often be unable to strip the top cartridge forward out of the magazine and into the chamber if the output force lifting and holding the top cartridge in a feed position were increased three and one third fold. The use of such force would often thus undesirably interfere with the automatic firearm cycle.
U.S. Pat. No. 2,217,848 discloses a four column magazine having a dividing wall that passes completely through the fore and aft interior space of the magazine (thus vertically dividing the magazine in two). Such a magazine uses two separate followers and springs so that each follower and spring must separately advance their respective two sets of cartridges with no positive connection between the two followers to synchronize their motion. Such separate, non-synchronized movement of the two sets of cartridges may result in the undesirable jamming of the magazine.
U.S. Pat. No. 4,589,218 discloses a four column magazine that has a fore and aft dividing wall and uses a single follower to advance all four columns, including advancing the last round, to the feed position. However, a single follower that will advance all four columns of cartridges cannot readily be made to continue upwardly through a double column portion of a magazine. Such double column magazines or portions of magazines are required so as to fit the magazine well of a firearm within the M4/M16 family of weapons, whose interface dimensions for the magazine fit have been recommended as a NATO standard.
In view of the foregoing, it would be beneficial to provide an improved box magazine, such as a box magazine that has increased capacity and/or enhanced reliability with respect to contemporary magazines.